US2418719A - Brake element - Google Patents

Description

Patente Apr.

naa ELEMENT William Mann, Grosse Pointe, Mich., assigner to The Budd Company, Philadelphia, Pa., a coinporation of Pennsylvania Application August 31, 1944, Serial No. 552,131

4 Claims. i

The invention relates to a brake element having a lining of the composition type.

Such brake elements as composition brake shoes cooperating with an opposed rotary brake element are commonly comprised of a. metal (ci. iss- 251) -it is not subject to the deterioration of the rubbacking to which the composition lining is secured. Some such composition linings yare rel-A tures are developed in localized regions of ex cessively high pressure, which may result not only in producing heat checks in the rotary brake elements, which are undesirable, but also increase the wear of the lining due both to the higher temperatures and the presence of heat checks.

It has, heretofore, been proposedto equalize the pressure on the working face of the lining by employing a rubber cushion between the lining and the metal backing and this has eliminated these diiiiculties for the most part. However, the rubber cushion was likely to deteriorate in time due to the high temperatures to which ltn was subjected in use, and also due to rapid change in temperature to which it was subjected in its use on vehicles, such as railroad trains, operating in regions where the normal temperature ranged from below zero to over 100 Fahrenhelt and the braking temperature between the lining and rotary brake element might rise up to 800 or more. Furthermore, if the lining was not changed before it wore quite thin, this differential temperature effect on the rubber was still more marked. To overcome these defects of the rubber backing and at the same time retain its advantages, and provide still other advantages, forms an object of the present invention.

This object is attained by a braker element or shoe having secured to its metal backing a lining varying in its characteristics from the-face of the backing to the wear face of the lining, the layer of lining adjacent the shoe being relatively soft and yielding, while the layer adjacent the wear face being relatively hard and unyielding and having superior braking and wear resisting qualities. The yielding layer acts similarly to the rubber formerly used in distributing the braking pressure evenly upon the wear face of the lining from the backing plate, at the same time ber due to the great and sudden changes of temperature encountered in service. Yet more, the outer wear-resisting and harder layer can be worn down further before requiring replacement withoutaflectlng the cushioning layer of lining and braking may still be had'even if all `the `outer layer is worn down by braking on the more yielding layer. Thus longer'tinle between re placement of the outervlayer of the lining is made possible and this Without running the danger of deleterlously affecting the cushioning inner layer adjacent the backingk plate.

Furthermore. with this arrangement the' outer layer, when worn down, may readily be replaced by simply cementing a new layer to the unused part of the multilayer lining.

Other and further objects and advantages and the manner in which they are attained will become clear from the following detailed description when read in connection with the drawings y forming a part of this specification.

In the drawings:

Fig. 1 shows one manner of application of the brakeelement of the invention, this view being aplan view of one-quarter of a railway truck having a brake applied to its wheel and axle assembly;

Fig. 2 is a. face view 'of a to the invention;

brake shoe according Fig. 3 is an edge View of the shoefwith parts broken away to show a detail, and

Fig. 4 is a View similar to Fig. 3 showing a slight modification.

The invention has been` shown vapplied in Fig. 1 to a railway truck having a frame i0 spring supported from a wheel and axle assembly ll through equalizer bars l2. The wheel and axle assembly carries a brake disc I3 the opposite faces of which are engageabley by the spaced segmental'shoes it which are carried from av support yoke l5 by levers i6 pivoted at Il, on

the support and between the ends of the levers opposite the ends thereof carrying the shoes, and operative to press ment of the invention is merely illustrative, for

the invention may be used in widely different brake embodiments.

As shown in Figs. 2 and 3, the shoe It compivotally connected to the shoes, k at i8. The actuating means for the levers may i comprise a i'luid pressure cylinder IS disposed prises the metal backing 20. of arcuate form against one i'ace of which is secured a composition lining. In the embodiment shown. this lining is constituted of spaced keystone-shaped blocks 2| extending across the width of the backf cemented, as indicated at 24, an outer layer 25 oi' composition lining material.

l 'I'he lining material of the two layers differs in 4 bodiments shown and the invention may be applied in other relations without'departing from the main features thereof, and such changes and modifications are intended to be covered in the appended claims.

What is claimed is:

1. A brake element having a rigid metal backing, a composition brake lining secured to said backing and having braking effectiveness for substantially its entire thickness, and means securing said lining to the backing, said lining having varying characteristics in the direction of its thickness. the portion of the lining adjacent the backing having the characteristic of being relatively soft and yielding and the portion of the lining adjacent the braking face having the charvacteristic of being relatively hard and unyieldlng,

yieldabllity and hardness and preferably also,

differs in wear resisting qualities, the inner layer 23, for the purposes of the invention, to enable it to serve as a cushioned support for the outer layer 25 from .the backing, being relatively soft and yielding in character. The outer layer 25,

on thev other hand, to enable it to resist wear, is'

relatively hard and unyielding in character. As shown, the two layers are substantially equal in thickness, but this particular thickness relation may -b'e changed without departing from the invention.

With this arrangement, it will be seen that the inner layer cushions the outer layer and allows it to adjust its wear lace to the: rotary brake element with substantially equal pressure throughout. At the same time, the yielding inner layer of composition lining is able to withstand the heat normally encountered in braking and may even itself become the wear face of the lining if the outer harder, wear resisting material is worn oft'. This makes it possible to wear down the outer layer 25 almost to, or to, the face of the inner layer before replacement and replacement can be` eected by simply cementing a new layer in place on the remainder of the worn lining. At the same time, if the wear should proceed beyond 'the outer layer before replacement was made, no harm would result, since the brakes would still be effective through the engagement of the inner layer with the rotary brake member.

According to the form shown in Fig. 4, the

inner and outer layers 26 and 21 may be molded,.`

if desired, in a single block,"28,'t'he inner vlamination of which has the soft and yielding character- 'istics similar to the block 23 of the preferred form and the outer lamination 29 of which has the hard and unyielding characteristicsof the outer layer 25 of the preferred form. In this case theholes for receiving the rivets 22 will have to be extended to the braking face of the outer layer 21,

as shown, where rivets are used as the securing and said means securing the lining to the backing terminating short of the outer i'ace of said porprising a laminated structure including at least two laminae, one lamina next to thebacking being relatively soit and yielding and one next to the braking face being relatively hard and wear-resisting, and said means securing the lining to the backing being associated solely with said lamina next to the backing.

3. A brake element having a rigid metal backing, a nrst layer of'compositlon brake lining secured to said backing, means securing it to the backing of an extent from said backing materially less than the thickness of said layer and a second layer of composition brake lining cemented to said rst layer, the first layer being relatively soft and compressible and the second said layer being relatively hard and less compressible than said rst layer.

4. A brake element having a rigid metal backing, a. composition brake lining koit substantial thickness secured thereto and having braking ei'- iectiveness forv substantially its entire thickness,

and means for securing said lining to the backing,

and said securing means for said lining termithe lining thickness.

REFERENCES CITED The following references are 'of record in the le of this patent:

UNrrED s'rA'rEs PATnNTs nating short of said half medium.

While several speciilc embodiments of the in- Number Name Date vention havevbeen shown and described and the 1,784,994 Morris -v Dec. 16, i930 invention has been shown applied to a railway 2,158,337 Rasmussen May 18,- 1939 brake, it will be understood that changes and 2,033,968 Fether Mar. 17, 1936 modifications may be made in the speciilc em- 2,134,744 Wales Nov. 1, 1938

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